Sealing device with dynamic action, particularly for rolling bearings

ABSTRACT

Sealing device including a first annular element that can be coupled to a first fixed mechanical member, and a second annular element that can be coupled to a second rotating mechanical member, for protecting an annular compartment delimited between the members; the first element being provided with at least one annular sealing lip configured to interact with the second element, which has a radial edge of a flange portion arranged at an edge of a sleeve portion of the first element, thus forming with the latter a radial gap configured as a labyrinth seal; wherein the radial gap of the flange portion of the second annular element carries a plurality of depressions arranged in a crown, spaced adjacently to one another at the radial gap and configured to generate, as a result of the rotation of the second element, a dynamic effect (F) for the purpose of repelling any contaminants impelled towards said radial gap.

CROSS REFERENCE RELATED APPLICATION

This application is based on and claims priority to Italian ApplicationNo. 102019000017879, filed Oct. 4, 2019, under 35 U.S.C. § 119 theentire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a sealing device with dynamic action,particularly applicable to, or in the presence of, a rolling bearinginserted between a first and a second mechanical member rotatingrelatively to one another, for example including the inner ring and theouter ring of the rolling bearing, for the purpose of protecting thebearing and/or the rolling bodies of the bearing from externalcontaminants, while simultaneously retaining any lubricating greaseinside.

BACKGROUND

As is known, it is currently a requirement in industry that a sealingdevice, of what is known as the “pack seal” type for example, forinsertion between two members in relative rotation, should have agreater sealing capacity combined with a lower friction torque than inthe past. There is also an increasing demand for seals that have lowfriction without any reduction in their fluid-tightness.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theappended drawings, which show some non-limiting examples of embodimentsof the invention, in which:

FIG. 1 shows schematically a view in three-quarter front perspective andin radial section of a sealing device according to this disclosure; and

FIGS. 2-7 show schematically the same three-quarter front perspectiveview, in radial section and truncated for simplicity, of variousembodiments of the sealing device in accordance with this disclosure.

DETAILED DESCRIPTION

One way to reduce friction in a sealing device is to reduce the numberof sealing lips in sliding contact with one of the two members inrelative rotation, or to form one or more lips configured to providenon-sliding labyrinth-type seals, but this usually entails a reductionin the sealing capacity of the sealing device.

With reference to FIG. 1, the number 8 indicates the whole of a sealingdevice that is generally insertable between a first annular mechanicalmember 5 and a second annular mechanical member 6, shown purelyschematically and only partially in broken lines, these members beingfitted, in a known way which for simplicity is not shown, in arelatively rotating way, the member 5 being the member rotating aboutits own axis of symmetry and the member 6 being the fixed member; forexample the members 5 and 6 may be, respectively, the rotating innerring and the fixed outer ring of a rolling bearing, or may be twomachine members made to be relatively rotational by means of a rollingbearing interposed between them.

In order to protect an annular compartment 7, delimited between therelatively rotatable members 5 and 6, from any external contaminants,and/or to retain any lubricating fluid in the annular compartment 7,inside a rolling bearing for example, the sealing device 8 is insertedbetween the members 5 and 6, coaxially with these members, asillustrated in a non-limiting way.

In fact, the sealing device 8 can be inserted between any two relativelyrotatable annular members, and therefore the following descriptionrefers to the mechanical members 5 and 6 purely by way of example,without thereby losing its generality.

The sealing device 8 comprises a first annular element 9 having a firstsleeve portion 10, which is the radially outer portion in theillustrated example, configured for coupling in an angularly fixed way,in use, to the member 6, which is stationary in use, and a first flangeportion 11 which extends in cantilever fashion from a first edge 12 ofthe sleeve portion 10 in a first radial direction, which in theillustrated example runs radially inside the sleeve portion 10.

The sealing device 8 also comprises a second annular element 13,positioned coaxially with the first annular element 9 and comprising asecond sleeve portion 14, which is the radially inner portion in theillustrated example, configured for coupling in an angularly fixed way,in use, to the member 5, which is rotating in use, and a second flangeportion 15 which projects from a first edge 16 of the second sleeveportion 14 opposite the edge 12; the flange portion 15 extends in aprojecting manner in a radial direction opposite to the radial directionin which the flange portion 11 extends in a projecting manner; in theillustrated example, this second radial direction runs radially outsidethe sleeve portion 14.

The second flange portion 15 faces the first flange portion 11, and moregenerally the second annular element 13 is inserted within the firstannular element 9, radially inside the latter and coaxially with it.

The first element 9 is provided with at least one elastically deformableannular sealing lip 18, which, in the non-limiting preferred exampleillustrated, is configured for interacting slidingly with a frontalsurface 19 of the second element 13, facing towards the first element 9.Alternatively, the annular sealing lip 18 may be configured to benon-sliding, but for forming a labyrinth seal with the frontal surface19.

Evidently, as will be seen, it is possible and often preferable forthere to be a plurality of annular sealing lips 18, configured forforming radial or axial sliding or labyrinth seals, according toconfigurations which are known as a whole and are therefore notillustrated for the sake of simplicity.

In the illustrated non-limiting example, the annular element 9 is formedby an annular sealing element 20 and an annular reinforcing element orsupport, 21, preferably made of metal, which has been fixed to theannular sealing element 20, preferably by bonding in the course ofvulcanization.

In the illustrated example, the element 9 is provided with a pluralityof annular sealing lips, consisting of three annular sealing lips 18 inthe illustrated example, of a known type and configuration, which extendradially and/or axially in cantilever fashion from the flange portion11.

The lips 18 form an integral part of the annular sealing element 20 andare preferably configured for interacting slidingly and with slightinterference on annular elements or shields 9 and 13, which are coupledto the flange portion 14 by means of the two radially inner lips 18 andto the sleeve portion 15 by means of the radially outer lip 18, all onthe frontal surface 19. Alternatively, one or more of the lips 18 may beconfigured for interacting with the flange portion 14 and/or with thesleeve portion 15 without sliding, but closely to these portions so asto form a labyrinth seal. In both cases, the annular element 13therefore serves as an additional component acting as a counter-face forthe annular sealing element 20.

According to an arrangement which is known, but which forms an integralpart of the present disclosure, in combination with what has beendescribed above, the second annular element 13 is configured to interactwith the first annular element 9, the elements 9 and 13 being coupledcoaxially (and, in the illustrated non-limiting example, with the secondinside the first as described above), so that a radial edge 22 of thesecond flange portion 15 is positioned at a second edge 23 of the firstsleeve portion 10, thus forming with the latter an annular radial gap 24configured to form a labyrinth seal between the first annular element 9and the second annular element 13.

According to a first aspect of some embodiments in accordance with thisdisclosure, the radial edge 22 of the flange portion 15 carries aplurality of depressions 25 arranged in a crown, spaced adjacently toone another in sequence along the whole radial edge 22, and positionedat the radial gap 24, immediately facing and adjacent to the edge 23 ofthe sleeve portion 10 of the element 9. Additionally, the depressions 25face in the opposite direction from the flange portion 11 of the element9, and, especially, are formed on a frontal face 26 of the element 13opposite the frontal surface 19 and belonging to the flange portion 15.

The depressions 25 are configured to generate, as a result of a rotationof the second annular element or shield 13 relative to the first annularelement or shield 9 and in interaction with the second edge 23 of thesleeve portion 10, because of the presence of the radial gap 24, adynamic centrifuging effect F, which for example is directed not onlytangentially but also axially and/or radially, and which is capable ofrepelling any contaminants impelled towards said radial gap 24, so thatthey are unable to reach it, thereby eliminating the risk that anycontaminant may penetrate the labyrinth seal formed by the gap 24 andenter the annular space between the shields 9 and 13, thus reaching thesealing lip 18 nearest to the flange portion 10, which in theillustrated example is the radially outer lip.

This dynamic centrifuging effect F is greatly improved in terms offorce, direction and path by the presence of the depressions 25, bycomparison with, for example, conventional centrifuging elements, sinceit can throw any solid contaminants far from the gap 24, thecontaminants being intercepted by the depressions 25, and when liquid orsimilar contaminants (such as water, mud, etc.) are present this flow isdiverted by the depressions 25, which act as the blades of a turbine.

According to a further aspect of some embodiments in accordance withthis disclosure, the depressions 25 alternate with solid circumferentialportions 27 with no discontinuities of the radial edge 22, theseportions 27 being spaced apart from the edge 23 of the sleeve portion 10by a quantity equal to the gap 24.

According to one aspect of some embodiments in accordance with thisdisclosure, the depressions 25 are also formed across the radial edge 22of the flange portion 15, on the side opposite the frontal surface 19,so as to extend partially on the face 26, which in turn faces in theopposite direction from the first element 9.

According to another aspect of some embodiments in accordance with thisdisclosure, the depressions 25 have a profile such that respectiveopposite lead angles α and β are formed with the radial edge 22 of theflange portion 15 on the face 26 (FIG. 3).

These angles α and β may preferably be symmetrical with one another, sothat the dynamic effect F generated by the depressions 25 is identical,independently of the direction of relative rotation between the firstand second element 9 and 13; alternatively, the opposed lead angles αand β are asymmetrical with one another, so that the intensity of thedynamic effect F generated by the depressions 25 varies with thedirection of relative rotation between the first and second element 9,13. The latter characteristic may be useful when the rotating member 5has a preferred direction of rotation.

With reference to FIGS. 2 to 7, these illustrate schematically variousembodiments described up to this point, indicated by the referencenumerals 8 a to 8 f For the sake of simplicity, details similar oridentical to those described previously are indicated with the samenumbers.

As shown in FIGS. 5, 6 and 7, the depressions 25 and the solid portions27 are defined by a wavy profile 28 carried by the radial edge 22 of theflange portion 15 on the side opposite to the flange portion 11 of thefirst element 9.

According to the variants shown in FIGS. 2, 3 and 4, however, thedepressions 25 are formed on or in the edge 22 and are spaced apart by aconstant interval, so as to leave between them the solid portions 27,consisting of intact portions 27 of edge 22.

According to preferred embodiments, indicated by 8 (FIG. 1), 8 a, 8 b, 8d, 8 e, the second element 13 (FIGS. 1, 2, 3, 5 and 6) comprises asubstantially rigid annular reinforcing element 29, preferably made ofmetal, delimiting both the flange portion 15 and the sleeve portion 14,and an annular insert 30 made of a synthetic or elastomeric plasticmaterial, preferably co-moulded in one piece or bonded duringvulcanization on the annular reinforcing element 29 on the side oppositeto the first element 9. Alternatively, the annular insert 30 may also besimply bonded to the annular reinforcing element 29, or may be fixed toit by snap-fitting.

The insert 30 forms, with the annular reinforcing element 29, the radialedge 22 of the second flange portion 15 of the second annular element13.

According to these embodiments, the depressions 25 are formed solely ona first radial edge portion 31, which in the illustrated example is theradially outer portion, of the insert 30, facing towards the sleeveportion 10 of the first element 9.

According to the embodiments indicated by 8, 8 a and 8 d (FIGS. 1, 2 and5), the annular insert 30 extends, according to the illustratedexamples, over the whole frontal face 26 of the flange portion 15 of theelement 13, which is opposite the element 9. It is also possible for theinsert 30 to extend over only an annular portion, which is the radiallyouter portion in this case, of the frontal face 26.

In the non-limiting embodiments indicated above, the insert 30 not onlycomprises the radial edge portion 31 but also comprises a second radialedge portion 32 facing in the opposite direction from the sleeve portion10 of the first element 9, which in the illustrated example is theradially inner portion, formed in one piece with the first radial edgeportion 31.

The radial edge portion 32, according to the preferred but non-limitingembodiments illustrated, is configured to form an encoder element, of aknown type, having a circumferential sequence of radial portions 33having physical or magnetic discontinuities, these portions, in theillustrated examples, being magnetized with opposite polarities, N(north) and S (south). If the insert 30 is not required to actadditionally as an encoder, then clearly these physical or magneticdiscontinuities are not present, even when the annular insert 30extends, according to the illustrated examples, over the whole frontalface 26.

Finally, in the embodiments 8 c and 8 f (FIGS. 4 and 7), the secondelement 13 is formed solely by a substantially rigid annular element 34,preferably made of metal, delimiting both the flange portion 15 and thesleeve portion 14.

In this case, the flange portion 15 comprise a protruding annular radialportion 35, projecting in cantilever fashion in an axial direction onthe opposite side from the first element 9 and delimiting/defining theradial edge 22 of the flange portion 15.

According to these embodiments 8 c, 8 f, the depressions 25 are formedon the protruding annular radial portion 35 on the opposite side fromthe first flange portion 11.

In the embodiment 8 c of FIG. 4, the depressions 25 are formed fromhollows or indentations produced by plastic deformation ofcircumferential portions of the annular radial portion 35, alternatingwith non-deformed portions which therefore form the solid portions 27.

In the embodiment 8 f of FIG. 7, the depressions 25 are formed by thewave troughs of the wavy profile 28, while the wave crests form thesolid portions 27 that are free of discontinuities. The wavy profile 28is formed by plastic deformation of the whole edge 22, bymoulding/embossing for example.

Similarly, in the embodiment 8 d of FIG. 5, in this case also thedepressions 25 are formed by the wave troughs of the wavy profile 28,while the wave crests form the solid portions 27 that are free ofdiscontinuities, and the wavy profile 28 is formed by injection mouldingor compression directly on the insert 30, during the step of mouldingthe insert.

Finally, it is evident from the above description that variousembodiments described herein also relates to a sealing system 36(FIG. 1) comprising a sealing device 8 according to any of theembodiments described above, and a first and a second annular mechanicalmember, such as the members 5, 6, coupled together so as to berelatively rotatable, in which:

-   -   the first element 9 is attached in an angularly fixed way to the        annular member 6 that is stationary in use,    -   the second element 13 is attached in an angularly fixed way to        the annular member 5 that is rotating in use,    -   the first element 9 is housed within the annular compartment 7        delimited between the first and second annular members numbered        5 and 6 in the non-limiting illustrated example,    -   the second element 13 is positioned radially inside the first        element 9 and towards the outside of the annular compartment 7,        on the opposite side from the first element 9, so that its        flange portion 15 substantially closes off the compartment 7        (except for the gap 24) from the external environment.

The object of the present invention is to provide a sealing device thatis free of the drawbacks of the prior art, while being reliable andeconomical, and particularly one that permits a reduction of thefriction created in use by the sealing device, and therefore thefriction torque, with its consequent energy consumption, by reducing thenumber of sealing lips configured to be slidingly coupled, in use, toone of two members in relative motion, but without losing sealingcapacity, or, conversely, one that permits an increase in the sealingcapacity without increasing the friction torque, or in the presence oflips configured for labyrinth seals only.

According to the invention, therefore, a sealing device insertablebetween a first and a second mechanical member in relative rotation,between the rings of a rolling bearing for example, is provided,together with an associated sealing system, with the characteristicsdisclosed in the attached claims.

Because of the favourable phenomenon consisting in the generation of thedynamic effect F, and according to other possible embodiments, the outerlip 18 may even be eliminated in order to reduce the friction (ifsliding lips are present), or alternatively the interference found atthe design stage between the lips 18 and their sliding surface 19 may bereduced even without varying the number of lips 18, again with the aimof reducing friction.

All the objects of the invention are therefore achieved.

1. A sealing device insertable between two relatively rotatablemechanical parts, comprising: a first annular element having a firstsleeve portion configured to integrally angularly couple, when in use,to a first of said mechanical parts, stationary in use; a first flangeportion that extends in a cantilever fashion from a first end of thefirst sleeve portion in a first radial direction; a second annularelement, arranged coaxial to the first annular element and comprising asecond sleeve portion configured to integrally angularly couple, when inuse, to a second of said mechanical parts, rotating in use; and a secondflange portion that extends in a cantilever fashion from a first end ofthe second sleeve portion, in a second radial direction opposite to thefirst, the second flange portion being arranged facing the first flangeportion; wherein the first element is provided with at least an annularsealing lip, elastically deformable, that is configured to cooperate insliding manner or with a labyrinth seal with a frontal surface of thesecond element, facing the first element.
 2. The sealing device of claim1, wherein the second element is configured to cooperate with the firstelement so that a radial edge of the second flange portion arranged at asecond end of the first sleeve portion forms, with the latter, a radialannular gap configured to provide a labyrinth seal between the first andthe second elements; wherein said radial edge of the second flangeportion carries a plurality of depressions arranged in a crownadjacently spaced from one another in sequence along the entire radialedge of the second flange portion and arranged at said radial gap,facing and adjacent to the second end of the first sleeve portion of thefirst element and arranged on the side opposite to the first flangeportion of the first element.
 3. The sealing device of claim 2, whereinsaid depressions are configured to generate, in response to the rotationof the second annular element and in cooperation with the second end ofthe first sleeve portion, a dynamic effect (F) designed to reject anycontaminants directed towards said radial gap.
 4. The sealing device ofclaim 3, wherein said depressions alternate with circumferentially solidstretches having no discontinuities of said radial edge of the secondflange portion, which stretches are spaced apart from said second end ofthe first sleeve portion, by a quantity equal to said gap.
 5. Thesealing device of claim 3, wherein said depressions are formed astridesaid radial edge of the second flange portion, so as to partly extendover a face of the second flange portion arranged on the side oppositeto the first annular element.
 6. The sealing device of claim 3, whereinsaid depressions are defined by a wavy profile carried by the radialedge of the second flange portion on the side opposite to the firstflange portion of the first element. The sealing device of claim 3,wherein said depressions have a profile such as to form with said radialedge of the second flange portion, on a face of the second flangeportion arranged on the side opposite to the first annular element,respective opposite lead angles (α, β) symmetrical with one another, sothat the dynamic effect (F) generated by the depressions is identicalindependently of the rotation direction of the second annular element.8. The sealing device of claim 3, wherein said depressions have aprofile such as to form with said radial edge of the second flangeportion, on a face of the second flange portion arranged on the sideopposite to the first annular element, respective opposite lead angles(α, β) asymmetrical with one another, so that the dynamic effect (F)generated by the depressions has a different intensity according to therotation direction of the second annular element.
 9. The sealing deviceof claim 3, wherein said second annular element (13) comprises asubstantially rigid annular reinforcing element, preferably made ofmetal, delimiting said second flange and sleeve portions, and an annularinsert made of a synthetic or elastomeric plastic material fastenedintegrally to the annular reinforcing element, preferably co-moulded onthe annular reinforcing element, on the side opposite to the firstannular element and defining with the annular reinforcing element saidradial edge of the second flange portion of the second annular element;said depressions being formed exclusively on a first radial end portionof the insert facing the sleeve portion of the first annular element.10. The sealing device of claim 3, wherein said annular insert extendsthroughout a frontal face of the second flange portion of the secondannular element opposite to the first annular element, or on an annularportion thereof, and comprises a second radial end portion arranged onthe side opposite to the sleeve portion of the first annular element andformed integrally with the first radial end portion.
 11. The sealingdevice of claim 10, wherein the second radial end portion is configuredto create an encoder element, having a circumferential sequence ofradial portions having physical or magnetic discontinuities.
 12. Thesealing device of claim 8, wherein said second annular element isconstituted by a substantially rigid annular element preferably made ofmetal, delimiting said second flange and sleeve portions; the secondflange portion comprising a projecting annular radial stretch,protruding in a cantilever fashion in an axial direction on the sideopposite to the first annular element and delimiting said radial edge ofthe second flange portion; said depressions being formed on saidprojecting annular radial stretch, on the side opposite to the firstflange portion.
 13. The sealing device of claim 3, further including: afirst and a second annular mechanical part coupled to one another sothat the second part is rotatable while the first part is stationary,characterized in that: the first annular element is integrally angularlyfixed to the first annular part, stationary in use, the first annularelement being housed inside an annular compartment delimited between thefirst and the second annular parts; and the second annular element isintegrally angularly fixed to the second annular part, rotating in use,the second annular element being arranged radially on the inside of thefirst annular element and towards the outside of said annularcompartment, on the side opposite to the first annular element.